In modern electronics, there is a steady trend towards the fact that the wiring is becoming more compact. The consequence of this was the emergence of BGA packages. Soldering these structures at home will be discussed by us in this article.
General information
Initially, many pins were placed under the microcircuit case. Thanks to this, they were located in a small area. This allows you to save time and create ever smaller devices. But the presence of such an approach in the manufacture turns into inconvenience during the repair of electronic equipment in the BGA package. Soldering in this case should be as accurate as possible and exactly carried out according to the technology.
What do you need for work?
Stock Up:
- Soldering station with hot air gun.
- Tweezers.
- Solder paste.
- Insulating tape.
- Braid for desoldering.
- Flux (preferably pine).
- Stencil (to apply solder paste on the microcircuit) or spatula (but it is better to stay on the first option).
Soldering BGA cases is not difficult. But in order for it to be successfully implemented, it is necessary to prepare the working area. Also for the possibilityrepetition of the actions described in the article, you need to talk about the features. Then the technology of soldering microcircuits in the BGA package will not be difficult (if you have an understanding of the process).
Features
Telling what the technology of soldering BGA cases is, it is necessary to note the conditions for the possibility of full repetition. So, Chinese-made stencils were used. Their feature is that here several chips are assembled on one large workpiece. Due to this, when heated, the stencil begins to bend. The large size of the panel leads to the fact that when heated, it takes a significant amount of heat (that is, a radiator effect occurs). Because of this, it takes more time to warm up the chip (which negatively affects its performance). Also, such stencils are made using chemical etching. Therefore, the paste is not applied as easily as on laser-cut samples. Well, if there are thermal seams. This will prevent the stencils from bending as they heat up. And finally, it should be noted that products made using laser cutting provide high accuracy (deviation does not exceed 5 microns). And thanks to this, you can simply and conveniently use the design for its intended purpose. This concludes the introduction, and we will study what the technology of soldering BGA cases at home is.
Preparation
Before you start soldering the chip, you mustapply strokes along the edge of its body. This must be done if there is no silkscreen that indicates the position of the electronic component. This must be done in order to facilitate the subsequent placement of the chip back on the board. The hair dryer should generate air with a heat of 320-350 degrees Celsius. In this case, the air speed should be minimal (otherwise you will have to solder the small thing next to it). The hair dryer should be held so that it is perpendicular to the board. Let it warm up for about a minute. Moreover, the air should not be directed to the center, but along the perimeter (edges) of the board. This is necessary in order to avoid overheating of the crystal. Memory is especially sensitive to this. Then you should pry the chip at one end and lift it above the board. In this case, you should not try to tear with all your might. After all, if the solder was not completely melted, then there is a risk of tearing off the tracks. Sometimes when you apply the flux and heat it up, the solder will start to form balls. Their size will be uneven in this case. And soldering chips in a BGA package will fail.
Cleaning
Apply alcohol rosin, heat it up and get the collected garbage. At the same time, please note that such a mechanism should never be used when working with soldering. This is due to the low specific coefficient. Then you should wash the area of \u200b\u200bwork, and there will be a good place. Then you should inspect the condition of the conclusions and evaluate whether it will be possible to install them in the old place. If the answer is negative, they should be replaced. That's whyboards and microcircuits should be cleaned of old solder. There is also the possibility that the “penny” on the board will be torn off (when using a braid). In this case, a simple soldering iron can help. Although some people use both a braid and a hair dryer. When performing manipulations, the integrity of the solder mask should be monitored. If it is damaged, then the solder will spread along the tracks. And then BGA soldering will fail.
Knurling new balls
You can use already prepared blanks. In this case, they simply need to be spread out over the contact pads and melted. But this is only suitable for a small number of pins (can you imagine a microcircuit with 250 "legs"?). Therefore, stencil technology is used as an easier method. Thanks to her, work is carried out faster and with the same quality. Important here is the use of high-quality solder paste. It will immediately turn into a shiny smooth ball. A poor-quality copy will break up into a large number of small round “fragments”. And in this case, it’s not even a fact that heating up to 400 degrees of heat and mixing with flux can help. For convenience, the microcircuit is fixed in a stencil. The solder paste is then applied using a spatula (although you can also use your finger). Then, while supporting the stencil with tweezers, it is necessary to melt the paste. The temperature of the hair dryer should not exceed 300 degrees Celsius. In this case, the device itself must be perpendicular to the paste. The stencil should be supported untilthe solder will not dry completely. After that, you can remove the mounting insulating tape and use a hair dryer, which will heat the air to 150 degrees Celsius, gently heat it until the flux begins to melt. After that, you can disconnect the microcircuit from the stencil. The end result will be smooth balls. The microcircuit is completely ready to be installed on the board. As you can see, soldering BGA cases is not difficult even at home.
Fastening
It was previously recommended to make finishing touches. If this advice was not taken into account, then positioning should be done as follows:
- Flip the IC so that it is pins up.
- Apply the edge to the nickels so that they match the balls.
- Fix where the edges of the microcircuit should be (for this you can apply small scratches with a needle).
- Fix first one side, then perpendicular to it. Thus, two scratches will be enough.
- We put the chip according to the symbols and try to catch nickels at the maximum height with balls by touch.
- Heat the work area until the solder is molten. If the previous points were executed exactly, then the microcircuit should fall into place without any problems. She will be helped in this by the surface tension force that the solder has. In this case, it is necessary to apply quite a bit of flux.
Conclusion
This is what is called "BGA chip soldering technology". ShouldIt should be noted that here a soldering iron, which is not familiar to most radio amateurs, is used, but a hair dryer. But despite this, BGA soldering shows good results. Therefore, they continue to use it and do it very successfully. Although the new has always scared many, but with practical experience, this technology becomes a familiar tool.
